Conventionally, with respect to a method for decorating surfaces of molded products, there has been known a method which inserts, into a metal mold, a decorating sheet having a base sheet provided thereon with designs and the like, then closes the metal mold, then injects a molten resin into the cavity of the metal mold and, simultaneously therewith, adheres designs on the decorating sheet to a surface of the resin molded product for fabricating a decorated molded product (refer to JP-A No. 3-231821, for example).
FIG. 6 illustrates the structure of a metal mold for use in fabricating such a product through simultaneous injection-molding and decorating.
In the same figure, the metal mold includes a movable mold 50 and a stationary mold 51, and the movable mold 50 is provided with a cavity 52 for providing a molded product.
On the other hand, the stationary mold 51 is provided with a core 53 at a place corresponding to the aforementioned cavity 52 and, further, is provided with an injection gate 54 for injecting a molten resin.
A decorating sheet 55 is set between the movable mold 50 and the stationary mold 51. The decorating sheet 55 is generally formed from a laminated body constituted by a base sheet 55a, a mold release layer 55b, a peel layer 55c, a decorating layer 55d and a bonding layer 55e. The decorating sheet 55 is set such that the base sheet 55a faces the cavity 52.
The movable mold 50 and the stationary mold 51 are closed and, then, a molten resin 56 is injected through the injection gate 54 into the cavity to which the decorating sheet 55 adheres tightly. After the molten resin 56 is cured, the metal mold is opened, and the base sheet 55a is separated together with the mold release layer 55b from the molded product, thereby resulting in a decorated molded product.
Further, in a case where decorated molded products are successively formed, a feeding roll for feeding the decorating sheet 55 into the metal mold is placed above the metal mold, for example, and a wind-up roll for winding up the base sheet after designs are transferred therefrom is placed below the metal mold.
However, with the aforementioned simultaneous injection-molding and decorating method, when a gravure printing machine for forming a design layer has a cylinder outer circumference of 940 mm, for example, the maximum value of the size of decoration is limited to 940 mm, which has made it impossible to perform simultaneous injection-molding and decorating for decoration panels for large-sized televisions having lateral widths larger than 940 mm. As described above, the aforementioned conventional simultaneous injection-molding and decorating method imposes a constraint on the sizes of molded products which can be decorated.
As a matter of course, it is possible to apply simultaneous injection-molding and decorating to long molded objects, by increasing the diameter of the cylinder. However, it is not practical to introduce new gravure printing equipment for coping therewith.